Medical bandages for administering a drug, for example a vasodilator, to the skin are known to the prior art. For example, in U.S. Pat. No. 3,742,951 as issued to Zaffaroni, there is disclosed a medical bandage comprising a backing member defining one surface of the bandage, a pressure sensitive adhesive defining the other surface of the bandage, and disposed between the surface a drug reservoir. The reservoir in one embodiment is a solid matrix formed of a polymeric material having the drug dispersed therein. The polymeric matrix is permeable to the passage of drug and it releases it to a rate controlling membrane for metering the flow of drug from the device.
In U.S. Pat. No. 3,797,494 issued to Zaffaroni, there is described a medical bandage for administering drug percutaneously in which the drug may be mixed with a transport agent that enhances the penetration of the skin by the drug. The main components of this bandage are a backing member, a drug reservoir layer, a microporous membrane, and a contact adhesive layer. The patent indicates the rate of drug administration is controlled by the rate at which drug diffuses from the reservoir through the microporous membrane. In U.S. Pat. No. 3,996,934 issued to Zaffaroni, a medical bandage is disclosed comprising a backing member, a reservoir, a release rate controlling membrane, and a fastening sytem for securing the bandage to the patient.
In U.S. Pat. Nos. 4,031,894 and 4,262,003, patentee Urquhart et al disclosed a medical bandage comprising a reservoir of mineral oil and polyisobutene. The polyisobutene is used for imparting gel and adhesive properties to the reservoir. In U.S. Pat. No. 4,060,084, patentees Chandrasekaran et al disclosed a medical bandage used for providing chemotherapy transdermally by administering an initial dose followed by a constant dose.
While the above described medical bandages represent an advancement in the drug delivery art, it will be appreciated a further advancement in medical bandages can be made by providing a medical bandage that can deliver drugs from low to high diffusion rates, and at a substantialy constant rate useful for the management of medical situations where such need occurs.